My system seems to have suddenly developed a problem with bge. The  
link keeps going up and down like fxp, all my servers and  
workstations have either fxp and/or bge. PXE boot rom and Windows  
dual-boot are working fine.

...
bge0: watchdog timeout -- resetting
bge0: block failed to stop: reg 0x1400, bit 0x00000002
bge0: watchdog timeout -- resetting
...

To make matters more strange, booting windows seems to have fixed bge  
in NetBSD. Now it's working again when it wasn't previously, after  
about 10 cold boots of trying different kernels.